(Meth)acrylate derivatives having an isocyanate group are compounds useful in producing various functional polymers.
A common method for preparing the (meth)acrylate derivatives having an isocyanate group is to react a salt of (meth)acrylic acid and aminoalcohol ester, with phosgene. Alternatively, the derivatives are synthesized by reacting isopropenyloxazoline and phosgene. However, these methods have problems in that side reaction occurs which is addition reaction to the double bond of the (meth)acryloyl group, and polymerization is induced during the reaction because of the presence of double bonds, resulting in a loss.
Furthermore, dehydrochlorination of 3-chloropropionate derivatives having an isocyanate group has been proposed as a method for preparing the (meth)acrylate derivatives having an isocyanate group in U.S. Pat. No. 2,821,544 (Patent Document 1).
However, the patent document 1 describes only production of acryloyloxyethyl isocyanate by dehydrochlorination of isocyanatoethyl 3-chloropropionate with use of quinoline, a weakly basictertiary amine. Moreover, since the acryloyloxyethyl isocyanate and quinoline have a small difference in boiling point, vacuum distillation separation is difficult for the product obtained by the method of the patent document 1. Further, the dehydrochlorination is performed at high temperatures (160° C.), and therefore addition of large quantities of polymerization inhibitor is required to suppress polymerization of the acryloylethyl isocyanate yielded. As described above, the method of the patent document 1 cannot satisfy the industrial requirements.
Furthermore, the conventional methods have problems of much residual hydrolyzable chlorine in the product. The (meth)acrylate derivatives having an isocyanate group that contain much hydrolyzable chlorine possibly bring about adverse effects when used as materials in various applications. Therefore, it has been required that the hydrolyzable chlorine content in the product is reduced.